The invention discloses a method for preparing conducting polymer micro-nanofibers in a magnetic spinning mode. The method comprises the steps that 1, a magnetic spinning device is built, wherein the magnetic spinning device comprises a rotary collection disc with a permanent magnet; 2, a spinning precursor solution is prepared, wherein magnetic nano particles, high-molecular polymer and conducting polymer are mixed and dissolved in an organic solvent solution; 3, the magnetic spinning device is utilized for preparing conducting polymer micro-nano complex fibers, wherein the spinning precursor solution is injected into a feeding device, the feeding device is started, liquid drops on an opening of a spinning nozzle forms a jet flow under the effect of magnetic field force to be connected with the permanent magnet to be a bridge, a brushless direct-current motor is started to drive the collection disc to rotate, the ferrofluid jet flow is continuously pulled out under the effect of magnetic field force, and conducting polymer micro-nanofibers are wound and formed among vertical supporting columns of the collection disc. The method does not need the high voltage effect, reduces the production cost and potential safety hazards, is suitable for large-scale production and has the good application prospect, and the fibers are distributed in order.